You are going to think I am nuts... but here goes, I live here in FL & do not like to use an umbrella because I am afraid that it will attract lightning. In a regular rain, I will use it, but when we have our storms, there is no way that I will open one up. Beside the fact of attracting the lightning, the winds are usually whipping around & blow the umbrella.
In the theme parks I never use them no matte what. I am too afraid that I will poke someone that isn't watching where they are going (as well as me not watching). I have been poked & it isn't fun. I resort to my poncho, no matter how hot I am. Usually when the heavy rains come, it cools down somewhat. It is only just before it stops totally that you become really sticky from it. We carry baggies for each poncho. After we are done with them, we stick them in it's baggie & then back into the backpack/fannypack. When we get back to our room, we hang them up in the shower to dry & then repack for the next day.